1. Field of the Invention
The present invention relates to a tool holder for a drilling tool and, in particular, for an annular core bit.
2. Description of the Prior Art
Tool holder for conventional annular core bits with an inner thread, e.g., 1¼″ UNC or PIXIE, has a bit-side axial stop surface for axially supporting the core bit. A drawback of such releasable thread connections, e.g., according to U.S. Pat. No. 4,911,253, consists in laborious mounting of the core bit on the tool holder and its dismounting therefrom. Also, often, jamming of the thread connection occurs.
German Publication DE-37 44 091 discloses a tool holder for an annular core bit which permits quick mounting and dismounting of the core bit. The tool holder has an inner splined profile and two inner conical surfaces. The associated shanks of the annular core bits lead to an axial lengthening of the entire tool-holder-shank system.
U.S. Pat. No. 4,923,344 discloses a tool holder for quick mounting and dismounting an annular core bit having a special screw-in adapter with an outer thread provided at its bit-side end, and a short shank. The tool holder has a spline toothing for transmitting a torque, a hollow, freely rotatable flange with an inner thread for an axial locking, with coaxial displacement of the bit being effected exclusively via small axial annular end surfaces. Because of a relatively small distance between the annular end surfaces, the yield limits, which characterize a plastic deformation-free state, are also small. With annular core bits having large diameters, above 100 mm, the bending torques, which are generated during the use of the core bits, exceed those yield limits.
An object of the present invention is a tool holder for quick mounting and dismounting of annular core bit having a short shank and a large diameter.
Another object of the present invention is a shank for an annular core bit.
A further object of the present invention is to provide appropriate adapters for at least one of tool holders and shanks.